Oil prices plunged more than four per cent Monday after the United States and Iran announced they had reached a peace agreement to end months of a war that had roiled energy markets.

West Texas Intermediate was down 4.39 per cent at $81.15 a barrel in Tokyo after mediator Pakistan said the United States and Iran agreed to a peace deal and an “immediate and permanent” end to military operations on all fronts, including Lebanon.

“The Deal with the Islamic Republic of Iran is now complete,” US President Donald Trump swiftly confirmed with his own statement on Sunday.